Permeability tuned coupling device



Nov. 12, 1940. M. J. KIRK ET AL 2,221,217

PERMEABILITY TUNED COUPLING DEVICE Filed March 14, 1938 m ////////l C Q BY M01. FEED H. JJHEJ 4/ ATTORNEY.

Patented Nov. 12, 1940 PERMEABILITY TUNED COUPLING DEVICE Martin J. Kirk and Wilfred H. James, Chicago,

and William A. Schaper, Oak Park, Ill., assignors to Johnson Laboratories, Inc., Chicago, 111., a corporation of Illinois Application March 14, 1938, Serial No. 195,766

6 Claims.

Our invention consists of a permeability tuned coupling device in which first and second inductive windings are mounted in coupled relation, each of said windings being provided with an iron core which is movable relatively to the associated winding for tuning purposes, the cores being preferably of comminuted magnetic material, combined with a suitable binder and compressed into solid condition. The windings are electrically connected with fixed condensers forming a part of the coupling device, so that the said condensers eflect the greater part of the tuning of the circuits in which they are included, to a desired frequency, the adjustment of the cores being usually employed to accurately tune said circuits to resonance at the desired frequency, after the coupling device is elect cally connected for use. Our coupling device s intended principally for use as the coupling means between the intermediate frequency stages of radio receivers,- for exampleof ,the superheterodyne type.

In connection with coupling devices of the kind described, it is frequently desired that the tuningof the circuits of the coupling device may be effectedindependently of each other and from the same end of thecoupling device, for example the end thereof that is remote from the mounting plate supporting the device in the radio receiver. By our invention we provide novel means for effecting independent adjustment of the cores of the coupling device, from the same end of said device, and we also provide novel means for mounting the fixed condensers of the coupling device on the supporting structure thereof.

The above and other objects of our invention will more clearly appear from the description of the drawing illustrating our invention. in which Fig. 1 is a central, vertical, sectional view taken longitudinally through the coupling device, this view being to an enlarged scale and taken along the line ll in Fig. 2;

Fig. 2 is a vertical, sectional view of the structure illustrated in Fig. 1, taken along the line 46 -1;

Fig. 3 is a vertical, sectional view of the structure shown in Fig. 1, taken along the line 3-3: Fig. 4 is a vertical, sectional view of a part of the structure shown in Fig. 1, taken along the line 4-4, and

Fig. 5 shows in elevation, one of the stud screws preferably used in connecting parts of the structure shown in Figs. 1 and 2.

Similar numerals refer to similar parts 55 throughout the several views.

As shown in Fig. 1, our coupling device consists of a supporting bar or member H), for example, of brass or other suitable material, which is U-shaped, so that its end portions Illa and H10 extend substantially parallel with each other and 5 across the longitudinal axis of the device, the body portion of said member being adjacent and substantially 'parallel with one side wall of a metallic shielding can ll employed to enclose the coupling device. The end portions Illa and Illb of the member I0, are provided with apertures coaxial with the axis of the coupling device, to receive the end portions of a tube I! of insulating material, on which the inductance windings l3 and I4 of the device are mounted. To hold the tube It in place in the supporting member ID, the ends of said tube are preferably flanged outwardly against the outer surfaces of the end portions Illa and lb of said supporting member, as shown at In and HI). While the inductance windings l3 and I l may be of any desired size and proportions, we prefer to construct each of the windings in a plurality of parts, spaced from each other as indicated and connected in series with each other, all of the parts of each of said windings so connected, being herein designated as one of the inductance windings of the coupling device. The windings l3 and M are spaced from each other on the tube l2 by an amount that will efiect the desired degree of coupling between said windings, and magnetic cores l5 and iii are located in the tube l2 in inductive relation with the windings l3 and ll respectively, said cores being preferably of comminuted magnetic mate'- rial combined with a suitable binder and compressed into solid condition, and of an outer diameter to move freely in the tube l2 supporting them. While the cores l5 and I6 may have any desired form, we prefer to make them tubular to facilitate their connection with adjusting screws l1 and I8 by means of connecting members i9 and 20 of resilient material, for example rubber compound, which extend through the holes in the cores in compressed condition.

The end portion lb of the supporting member III, has secured to it by stud screws 2|, 2|, as illustrated in Fig. 2, a plate 22, for example, of metal or other suitable material which extends across the end of the tube l2 and clamps the flange [2b thereof against the end portion I017. The plate 22 is provided with a threaded aperture coaxial with the axis of the coupling device, for threaded engagement with the adjusting screw l8, so that by turning the said adjusting screw, the core It may be withdrawn towards the plate 22, from within the winding H, to any extent that may be desired, the core 16 being illustrated in Fig. l, in its completely inserted position relatively to the winding l4, and therefore in its position producing a maximum inductive effect of said winding. The upper end portions of the plate 22 and of the end portion Nib of the supporting member Iii, are provided with clearance apertures for an adjusting screw 23, having a flange "a frictionally held between the plate 22 and the upper end of the portion Mb. The adjusting screw 20 is disposed substantially parallel with the tube It and a washer 24 of resilient material, for example felt, is disposed between the flange Ila and the end portion lob of the supporting member ll, to prevent axial play of the adjusting screw 23, when the plate 22 is tightly clamped to the sup rting member by the adjacent screw II, without interfering with turning said screw fl for adjustment purposes. The threaded portion of the adjusting screw 28 extends through and engages corresponding threads in the downwardly bent end portion of an operating bar 26, which extends longitudinally of the device and through a guiding slo lllc in the end portion Ilia of the supporting member It. Outside of the end portion Ilia of the supporting member, the operating bar 25 is bent as indicated at 28a, substantially parallel with the end portion I04, and extends across the axis of the tube It, said bent end portion "a being provided with a threaded aperture coaxial with the tube I! for threaded engagement with the screw 11, which is held in any desired adjustment relatively to the operating bar by a clamping nut 26. As a result of this construction, turning the adjusting screw 28, moves the operating bar 25 longitudinally of the device and imparts corresponding axial movement to the core II for tuning purposes. The adjusting screws II and 23 extend through clearance apertures therefor in the can I I, so that said adjusting screws may be operated after the can is in place, and from the end of the coupling device remote from the plate on which the coupling device is mounted.

The shielding can II is held on the studs 2| by suitable nuts as indicated for one of said studs at 21 in Fig. 1, and the supporting member I0 is further held in place in said can by a screw II extending through said can into said supporting member. The can having the coupling device mounted therein as described, is conveniently supported on any desired mounting plate 29 by means of threaded lugs ill extending from the end of said can and engaging nuts 3| to hold the can in place.

As shown in Fig. 2, the plate 22 has extending therefrom a tongue 22a engaging the midportion of a spring 32, the end portions of which spring press against the adjusting screws l8 and 23 and tend to hold said screws in any adjusted positions.

The member II has secured thereto fixed condensers a and 84, by metal staples l5 and 36 extending around said condensers and through apertures in said supporting member so that the end portions of the staples are between the supporting member and the adjacent side wall of the shielding can II. The condenser 33 is connected with the terminals of the winding 13 by wires l1, l1 and the condenser 34 is connected with the terminals of the winding II by wires II. I.

As shown for the condenser 38 in Fig. 4, the outer insulating material of the cond nsers 8 provided with recesses Ila, Ila engaged by corresponding projections led formed on the upper surface of the supporting member ill to prevent lateral displacement of the condensers on the supporting member. As a result, the staples II and 88, by holding the recesses and projections securely in engagement with each other, prevent displacement of the condensers in any direction relatively to the supporting member.

The adjusting screws I1 is employed to secure proper position of the core II relative to the winding 3. when the adjusting screw 23 is in either of its positions of extreme adjustment, after which the nut 28 is tightened and the screw I1 is not further used in tuning the coupling device, all adjustments to compensate for the capacity of connecting wiring being eflected by the adjusting screws II and 23 for the circuits including the windings I4 and II respectively, so that each of said circuits may be accurately brought to a resonant condition at the frequency for which the coupling device is designed, after the coupling device is electrically connected with the apparatus with which it is to be used.

In making use of the expression permeability tuning in connection with the inductance windings, we refer to eii'ecting inductance changes in said windings, by changing the permeability of the magnetic paths of said windings by the movement of magnetic cores relatively to said windings.

While we have shown our invention in the particular embodiment above described, it is understood that we do not limit ourselves to the particular constructions illustrated in carrying out our invention, as we may employ equivalents thereof without departing from the scope of the appended claims.

Having thus described our invention, what we claim is:

1. In a permeability tuned intermediate frequency coupling device, the combination of a tube of insulating material, two inductance windings mounted on said tube and spaced for desired coupling between them, a core of compressed comminuted magnetic material in said tube for each of said windings, first and second adjusting screws connected respectively with said cores and extending from the ends of said tube to move the cores axially in said tube, a U-shaped bar having its ends engaging and supporting said tube, said bar ends being extended substantially beyond said tube, a plate secured to one end of said bar and extending across the adjacent end of said tube, said plate having a threaded aperture engaging the threads of said first adjusting screw, a third adjusting screw extending through said one end of said bar and through said plate and substantially parallel with said first screw, said third screw having a flange between said bar and said plate restraining said third screw from axial movement, and an operating bar having bent ends in threaded engagement respectively with said second and said third screws, whereby rotation of said third screw moves said operating bar longitudinally and thereby moves said second screw and the core connected therewith axially in said tube.

2. In a permeability tuned intermediate frequency coupling device, the combination of a tube of insulating material, two inductance windings mounted on said tube and spaced for desired coupling between them, a core of compressed comminuted magnetic material in said tube for each of said windings, first and second assist? adjusting screws connected respectively with said cores and extending from the ends of said tube to move the cores axially in said tube, a U-shaped bar having its ends engaging and supporting said tube, said bar ends being extended substantially beyond said tube, a plate secured to one end of said bar and extending across the adjacent end of said tube, said plate having a threaded aperture engaging the threads of said first adjusting screw, a third adjusting screw extending through said one end of said bar and through said plate and substantially parallel with said first screw, said third screw having a flange between said bar and said plate restraining said third screw from axial movement, an operating bar having bent ends in threaded engagement respectively with said secnd and said third screws, whereby rotation of said third screw moves said operating bar longitudinally and thereby moves said second screw and the core connected therewith axially in said tube, and a washer of resilient material engaging the flange of said third screw and tending to hold the latter in adjusted position.

3. In a permeability tuned intermediate irequency coupling device, the combination or a tube of insulating material, two inductance windings mounted on said tube and spaced for desired coupling between them, a core of compressed comminuted magnetic material in said tube for each of said windings, first and second adjusting screws connected respectively with said cores and extending from the ends of said tube to move the cores axially in said tube, a U-shaped member having its ends engaging and supporting said tube, said member ends being extended substantially beyond said tube, a plate secured to one end of said member and extending across the adjacentend of said tube, said plate having a threaded aperture engaging the threads of said first adjusting screw, a third adjusting screw extending through said one end of said member and through said plate and substantially parallel with said first screw, said third screw having a flange between said member and said plate restraining said third screw from axial movement, and an operating bar having bent ends in threaded engagement respectively with said second and said third screws, whereby rotation of said third screw moves said operating bar longitudinally and thereby moves said second screw and the core connected therewith axially in said tube, said operating bar having sliding engagement with said supporting member restraining said operating bar from lateral movement.

4. In a permeability tuned intermediate frequency coupling device, the combination of a tube of insulating material, two inductance windings mounted on said tube and spaced for desired coupling between them, a core of compressed comminuted magnetic material in said tube for each of said windings, first and second adjusting screws connected respectively with said cores and extending from the ends of said tube to move the cores axially in said tube, a U- shaped member having its ends engaging and supporting said tube, said member ends being extended substantially beyond said tube, a plate secured to one end of said member and extend ing across the adjacent end of said tube, said plate having a threaded aperture engaging the threads of said first adjusting screw, a third adjusting screw extending through said one end of said member and through said plate and substantially parallel with said first screw, said third screw having a flange between said member and said plate restraining said third screw from axial movement, an operating bar having bent ends in threaded engagement respectively with said second and said third screws, whereby rotation of said third screw moves said operating bar longitudinally and thereby moves said second screw and the core connected therewith axially in said .tube, and a spring pressing against said first and said third screws and tending to hold the same in adjusted positions.

5. in a permeability tuned intermediate frequency coupling device, the combination of a tube of insulating material, two inductance windings mounted on said tube and spaced for desired coupling between them, a core of compressed comminuteol magnetic material in said tube for each of said windings, first and second adjusting rods connected respectively with said cores and extending from the ends of said tube to move the cores axially in said tube, a mem ber adjacent one end of and supporting said tube, a plate secured to said member and extending across the end of said tube, said plate having an aperture receiving one of said first and sec- 0nd rods with threaded engagement, an adjusting screw having a fixed support spaced laterally from said tube, and an operating bar having bent ends respectively in engagement with the other of said first and second rods and with said screw, said screw having means restraining it from axial movement relatively to its said sup port.

6. In a permeability tuned intermediate frequency coupling device, the combination of a tube of insulating material, two inductance windings mounted on said tube and spaced for desired coupling between them, a core of compressed comminuted magnetic material in said tube for each 0! said windings, first and second adjusting rods connected respectively with said cores and extending from the ends of said tube to move the cores axially in said tube, a member adjacent one end of and supporting said tube, a plate secured to said member and extending across the end of said tube, said plate having an aperture receiving one of said first and second rods with threaded engagement, an adjusting screw having a fixed support spaced laterally from said tube, and an operating bar having bent ends respectively in engagement with the other of said first and second rods and with said screw, said screw having means restraining it from axial movement relatively to its said support, said fixed support including said member and said plate, and said restraining means comprising a flange on said screw between said member and said plate. 

